1. Field of the Invention
The present invention relates to missile systems. More particularly, the present invention relates to propulsion and control systems for missiles.
While the present invention is described herein with reference to an illustrative embodiment for a particular application, it is understood that the invention is not limited thereto. Those of ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications and embodiments within the scope thereof.
2. Description of the Related Art
Most winged missiles are controlled by aerodynamic surfaces or fins driven by hydraulic, gas pressure, motor bleed, electric, or other sources of power. As is widely known, the low speed during the initial flight of an earth-launched missile, provides limited aerodynamic force for controlling the missile path.
Thrust vector control (TVC) techniques have therefore been developed to enhance aerodynamic control during the initial launch period. These techniques have generally involved deflection or redirection of the missile exhaust flow to provide control moments. (See e.g., U.S. Pat. No. 4,274,610 issued Jan. 23, 1981 to Bastian). Particular TVC techniques involve the use of control vanes in the exhaust, injection of a volatile fluid within the exhaust, positioning of spoiler blades across the exhaust, and gimballed thrust chambers. These techniques have the universal disadvantages of wasting part of the main rocket thrust for steerage and of requiring major modifications to the missile exhaust structure or the missile body itself.
Although the integrated thrust vector control system of Maudal, (U.S. Pat. No. 4,044,970, issued Aug. 30, 1977) attempted to solve certain of the above problems, the Maudal system has significant shortcomings. The first is that it requires a thrust vector mechanism, or rocket motor, which is integral to the missile fin ("tail panel"). Since the thrust from the rocket motors passes through the fins, the fins must be designed to handle thrust loads. This adds to the weight of the missile and reduces its cost/performance ratio. Further, since the motor is permanently attached to the fin, the fin may not be balanced aerodynamically when the fuel supply of the motor is exhausted. In addition, the integral system of Maudal does not appear to allow for an inexpensive retrofit of existing missile systems.
Another shortcoming of a system constructed in accordance with the teaching of Maudal is that the TVC system would be designed to act in concert with the main missile propulsion system. This would be a significant disadvantage in that any activation of the main booster might leave a signature which would adversely impact on the survivability of the system. In addition, fuel may be expended in an undesired direction thereby limiting the range and effectiveness of the system.
An alternative to the use of TVC would be to bring the missile to a very high velocity quickly so that flight aerodynamics are adequate to provide the required steerage, as in air launch applications. A negative consequence of this technique in a ground launch mode is that the missile would rapidly achieve high elevation, and thereby experience reduced ability to hit close in targets. In addition, more boost energy may be used thereby possibly increasing the signature of the missile.
The above problems may be compounded with respect to a missile designed for both air-to-air and ground launched missions.